#include <stdio.h>
#include <stdlib.h>

// ./findh EINVAL
int main(int argc, char const *argv[])
{
    if(argc != 2) return -1;
    char cmd[128] = "";
    sprintf(cmd, "find /usr/include -name \"*.h\" |xargs grep -n -e %s", argv[1]);
    int ret = system(cmd);  
    return 0;
}